#include <stdio.h>
double f(double n)
{
    double t,s=1;
    int i;
    for (i = 1;i <=2 * n - 1;i++)
        s = s * n;
    t=1.0/s;
    return t;
}

int main() {
    int i;
    double sum = 0;
    double n;
    scanf_s("%lf", &n);
    for (i = 1;i <= n;i++)
        sum = sum + f(i);
    printf("%f", sum);
    return 0;
}